i was wondering do u balance a plane when it is full of gas or empty??

i knnoe this seems like a weird question but i do not know...

simple...empty!

The reason for checking the CG with the tank empty is to avoid creating a tail-heavy situation (usually a BAD thing) once the fuel supply is depleted. Most fuel tanks are positioned forward of the CG so being slightly nose heavy with a full tank of fuel is no problem.

thanx alot for your responses by any chance do u know if a ultra stick 40 assembled with quad flaps and mounting everything like the booklet using a saito .82 would this need to be altered any to achieve an ideal cg???

thanx

Don't know about that particular set-up but every plane has to checked before flying. Unless you've done something way out of normal it's usually just a matter of moving the battery pack, receiver, or possibly the servos until you get the CG correct. In some cases all of that still isn't enough and extra weight must be added where necessary. The manual should (usually) point you in the right direction as long as your engine is within the recommended range.

Good thing Crashem isn't reading this, lol.

He likes to demean beginners for asking how to balance a plane. I asked a question about how to balance a plane when I was starting last October, he still brings it up.

Stop whining and get to work on that chipmunk.

You're own construction methods can have a big affect on where weight is on the model so simply stating an engine to be used isn't really enough to say.
You should treat each model you build (with respect to CG) individually. For .40 and .60 size aircraft, one of the best techniques is to build the model but don't secure the radio equipment (especially the battery) in position yet. Then set up a CG stand and move the battery and servos around until you get the CG where you want it.
Using the weight of the radio system itself for balance is the best way to save weight, and in the event you still can't balance the model with the radio gear, at least you'll have to use that much less lead to finish the job.

I just finished a .60 3D aircraft and if balanced close, but once the fuel tank was 1/2 empty, it became a hanful on landing due to the rear CG. A 1-1/2 oz. prop shaft weight is all it took to make it fly pretty.

Highflight

Just for info I have never had amodel where changing the battery position would make a big differencd on the cg. [8D]

I have had to change the battery position on all of my planes so far. All my planes have called for a 40 size engine and I have been using a 46. They are nose heavy with the battery in front of the servos, they balance perfectly with the battery behind the servos.

I've had MANY planes where changing the location of the battery had a significant effect on the CG

i have just converted a wattage giles to i.c. and had to strip some covering off the fuselage to fit the battery as far back as i could get it to get the cofg right.

IF you get into low wings, don't forget to check the cg with the plane inverted. I use small circles of electrical stuck on the cg spots before I invert the plane. You can find them with your fingers without having to see them and they are easy to remove after.

I've had three low wing planes. I have check the balance of all of these right side up as the directions explain. They all were fine.

Please excuse my ignorance, but wouldn't the balance point be the same either way? The balance point is the fulcrum where there is equal leverage on either side, kind of like a teeter totter. How would turning it upside down affect this?

thanx for all the input i guess it just varies i will just ask some people at my field who have a cg stand. but i guess everyone has there own little ways to balance.

thanx

To answer your question you balance it with the tank empty. Follow the directions and you will be fine. I don't have a balance tool yet. I just use my fingers. It it not the most accurate in the world but its close enough. Just put a finger on each side of the wing on a rib at the distance from the leading edge that is specified.

It should lean forward just a tad but not nose over.

That is correct. It is sometimes easier to get the plane in a balanced position on the CG machine (or whatever is used) if there is more of the fuse hanging below the wing than above it. Hence the reason for inverting a low wing plane. The CG will not change, it is the same either way.

Just as MinnFlyer has stated, I have also had many planes where moving the batteries has a huge effect on the CG..... all of them now that I think about it.

Wings, it wasn't your question that I was demeaning it was your rude attitude in response to those members who took the time to not only explain to you how to balance the model but made the mistake (God forbid[X(]) of suggesting that you should seek experienced in person help before attempting to fly it alone if you didn't know how to balance it. I also remember many others posting similiar sentiments to your response in that same thread

But its good to see that you still fit Minnflyer's description


P.S. Its easier to balance low wings upside because the fuse acts as a pendelum.

I also do not have a balance tool.. But with another person around
I use the eraser end of a fat pencil.. to check my CG just outside
of the fuse... I do keep the wing at the top for eaiser checks.. All
that I have checked with my pencil method comes out right on
when checking with a fellow members CG tool... But the finger
at the recommended spot at the wing tips also works.

What is minnflyer's description?

People can get to know me by reading my post, and the same with you. Let each person decide for themselves who is rude. I am far from rude.

It was very helpful of you to point out something that was already pointed out. Way to be on top of things!